org.json4s.scalap.Memoisable.scala Maven / Gradle / Ivy
// -----------------------------------------------------------------------------
//
// Scalax - The Scala Community Library
// Copyright (c) 2005-8 The Scalax Project. All rights reserved.
//
// The primary distribution site is http://scalax.scalaforge.org/
//
// This software is released under the terms of the Revised BSD License.
// There is NO WARRANTY. See the file LICENSE for the full text.
//
// -----------------------------------------------------------------------------
package org.json4s.scalap
import scala.collection.mutable
trait MemoisableRules extends Rules {
def memo[In <: Memoisable, Out, A, X](key: AnyRef)(toRule: => In => Result[Out, A, X]) = {
lazy val rule = toRule
from[In] { in => in.memo(key, rule(in)) }
}
override def ruleWithName[In, Out, A, X](name: String, f: In => Result[Out, A, X]) = super.ruleWithName(name, (in: In) => in match {
case s: Memoisable => s.memo(name, f(in))
case _ => f(in)
})
}
trait Memoisable {
def memo[A](key: AnyRef, a: => A): A
}
object DefaultMemoisable {
var debug = false
}
trait DefaultMemoisable extends Memoisable {
protected val map = new mutable.HashMap[AnyRef, Any]
def memo[A](key: AnyRef, a: => A) = {
map.getOrElseUpdate(key, compute(key, a)).asInstanceOf[A]
}
protected def compute[A](key: AnyRef, a: => A): Any = a match {
case success: Success[_, _] => onSuccess(key, success); success
case other =>
if(DefaultMemoisable.debug) println(key + " -> " + other)
other
}
protected def onSuccess[S, T](key: AnyRef, result: Success[S, T]): Unit = {
val Success(out, t) = result
if(DefaultMemoisable.debug) println(key + " -> " + t + " (" + out + ")")
}
}